docs: def update_node(cls, cluster_id_label, command, private_dns, parameters=None):
          """
          Add a node to an existing cluster
          """
          conn = Qubole.agent(version=Cluster.api_version)
          parameters = {} if not parameters else parameters
          data = {"command" : command, "private_dns" : private_dns, "parameters" : parameters}
          return conn.put(cls.element_path(cluster_id_label) + "/nodes", data)